This invention relates generally to the testing of cables and wire harnesses, and more particularly concerns a novel tester apparatus that is expansible, as in modular mode or modes, to accommodate testing of different size wire harnesses, or multiple connectors on wire harnesses.
Cable testers are used to verify electrical specifications of conductors in cable and wire harnesses, as for example circuit continuity. In the past, different size testers were required in order to test different size wire harnesses.
Typically, a circuit tester apparatus tests an electric circuit by testing the electrical connections between all of the electrical points in that circuit. The tester apparatus includes elements called "test points" that are electrically connected to the electrical points in the circuit while the circuit is being tested. Typically, the tester apparatus includes one test point for each point in the circuit that is being tested, and so the number of test points in the tester apparatus must equal or exceed the number of points in the circuit being tested. A circuit with a large number of points can be tested only by a tester apparatus that has an equally large number of test points. Since one of the most expensive components of a tester apparatus is its test point circuitry, the cost of a tester apparatus is directly related to its number of test points.
Prior art tester apparatus uses carrier elements to which the circuit points of a cable or wire harness are electrically connected in order to be tested. The carrier elements include first electrical connectors which comprise terminal pins, and the tester apparatus includes second electrical connectors which comprise terminal pin receptacles. The carrier elements are interfaced to the second electrical connectors by interfitting the first electrical connectors to the second electrical connectors.
In prior art apparatus, it is acceptable for the number of circuit points to which an individual carrier element is connected to be less than the number of receptacles in the second electrical connector to which that carrier element is interfaced. However, in this situation, some of the receptacles in that second electrical connector are not utilized, and, as a result, some of the test points that are assigned to that particular second electrical connector are not utilized. This means that some of the test point capacity in the testing apparatus is wasted.
If such prior art tester apparatus is configured to include multiple carrier elements, and if the maximum number of circuit points to which each carrier element can be connected is less than the number of receptacles in each second electrical connector, then a certain number of the test points associated with each second electrical connector is wasted. As a result, because each test point in the tester apparatus is assigned to a specific second electrical connector, and because in this configuration the tester apparatus must include one second electrical connector for each carrier element, it is necessary for the tester apparatus to have a total number of test points that is significantly greater than the number of points in the circuit being tested. This means that a significant proportion of the test point capacity of the tester apparatus is wasted, and the cost of the tester apparatus is higher than it would be if the number of test points were limited to the number of points in the circuit being tested.
There is continuing need for simple, low-cost, tester apparatus that can readily interface to different size wire harnesses, and to multiple connectors to be simultaneously tested. This invention improves upon the tester apparatus disclosure in U.S. Pat. No. 5,072,185 to Rockwell.